Many boat owners transport their boats by towing them on a trailer that is pulled by a vehicle. When the boat is secured to the trailer for towing, it is common for the boat's propeller, located at the rear end of the boat, to overhang and extend beyond the edge of the trailer. Any overhang of the propeller creates a roadway safety hazard. For example, it is very difficult for drivers of vehicles traveling behind the boat towing vehicle to determine the depth of the propeller's overhang so the driver can determine the distance he or she needs to maintain between the vehicles. Without sufficient notice of the depth, a vehicle traveling behind the boat towing vehicle may not maintain a safe enough distance to keep from hitting the rear of the boat and trailer. This is even more of a hazard when traveling on an interstate at high speeds or at night. Some state statutes and regulations require that any trailer overhang be marked with some identification, such as an orange or red flag. However, these statues and regulations are rarely enforced. Additionally, the use of a flag is still insufficient to warn other drivers of the depth and size of a propeller overhang.